the zip archive needs to conform to the zip64 extensions to the zip spec.

The extensions to the zip spec are pretty straightforward.

It won't be a difficult task for me to do this. But it requires thought and testing.

For me, it's a matter of time and priorities. I'll have time later in December to do it.

What I need are sample zip64 archives that I can use to test the library against.

There was another person who even submitted some code that he said fixed the problem. And he was right, for the limited thing he was trying to do. But those changes did not deliver general support for zip64, which is what people want. There was no error
checking, there were no tests submitted with the changes, there was no support for writing large archives, there was no way in the programming interface to query if zip64 was in use, and so on. The changes worked for his scenario (I think it was reading a
specific archive), and I'm glad the library worked for his purpose. But to address what people really want - zip64 in all scenarios (writing, updating, reading broken or corrupted archives, etc) requires more changes.